As a radiation detector of a combination of a photomultiplier tube and a scintillator, for example, a radiation detector as disclosed in Japanese Patent Laid-Open No. Shou62(1987)-59884 gazette has been known.
FIG. 5 is a view illustrating a radiation detector 1 described in the said gazette. The radiation detector 1 has a constitution, in which a metallic container 3 accommodating a scintillator 2 is fixed to a faceplate, a light incidence plane plate member 5a of a photomultiplier tube 5 with an optical binder 4 interposed therebetween. The optical binder 4 also functions as adhesive.
On one of end of the metallic container 3, which is placed on a side of the light incidence plane plate member 5a of the photomultiplier tube 5, a light emission window 6 made of glass is applied. Accordingly, when radiation is incident on the scintillator 2, light is generated. Then the light is incident on the light incidence plane plate member 5a via the light emission window 6 and the optical binder 4 into the photomultiplier tube 5, where the light is converted into electric signals, which are amplified by the photomultiplier section 5c and focused on an anode 5d. 